Chemical application apparatus for sprinkler systems

ABSTRACT

A liquid chemical dispenser for an irrigation system comprises a removable supply container for the chemical which, in a first embodiment, comprises a valve for preventing spillage of the chemical during attachment of the container to the dispenser. This feature allows the container to be mounted in an inverted position on the dispenser without loss of its contents. In a second embodiment, the chemical container comprises a membrane which is pierced by a dip tube when the container is attached to the dispenser. A section of the dip tube produces an annular vent passage in the membrane around the dip tube to provide vacuum relief. The configuration of the containers substantially reduces the chance of inadvertent contact with the contents and the simple design permits the containers to be disposable.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a division of U.S. patent application Ser. No.11/424,773 filed Jun. 16, 2006, now issued as U.S. Pat. No. 8,746,593.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to irrigation systems. More particularly, itrelates to devices for adding liquid fertilizers, insecticides,herbicides, fungicides and the like to the water distributed by anautomatic sprinkler system.

2. Description of the Related Art

The availability of low-cost PVC pipe and solvent-welded PVC pipefittings has resulted in the widespread installation and use ofautomatic sprinkler systems. Such systems typically comprise a source offresh water under pressure (often a community water utility), a manifoldfor distributing the water into various zones each having a plurality ofsprinkler heads, a series of electrically-actuated valves forcontrolling the flow of water in each of the zones, a timer for openingand closing the valves at pre-selected times or time intervals, and abackflow prevention device for keeping possibly contaminated water fromre-entering the supply system.

An in-ground, automatic sprinkler system presents the opportunity toconveniently distribute water-soluble chemicals such as fertilizers,weed killers, fungicides, and insecticides to areas served by thesystem. A number of United States patents concern devices for addingwater soluble chemicals to sprinkler and irrigation systems.

U.S. Pat. No. 7,011,254 to Thornton describes a lawn chemicalapplication system that comprises a dispenser having a lower chamber, anupper chamber, an upstream opening, and a downstream opening. Thedispenser may be formed by a tee connector and a cylinder secured to anupper opening of the tee connector. Powered valves are operablyconnected to the upstream and downstream openings of the dispenser. Thepowered valves may be wired to open and close simultaneously. A lowerportion of the upper chamber may be disposed below an upper portion ofthe lower chamber and above a lower portion of the lower chamber,leaving the lower portion of the lower chamber unobstructed oversubstantially its entire length. The lower portion of the upper chambermay have a plurality of openings to provide for adequate mixing of waterwith the chemicals stored in the upper chamber. In operation, solublematter or other chemicals are placed in the upper chamber of thedispenser, and the two valves are opened simultaneously. Water flowsthrough the first powered valve and into the dispenser, where the wateris mixed with soluble matter or other chemicals stored in the upperchamber of the tee. The solution or mixture then passes from thedispenser, through the second powered valve, to one or more sprinklerheads of the irrigation system. When the application is finished, thevalves are closed simultaneously.

U.S. Pat. No. 6,997,350 to Johnson et al. describes an apparatus foradding liquid fertilizer to a water line of a sprinkler system. Theapparatus includes a mechanical injector device powered by a paddlewheel turned by water flowing through the water line. The mechanicalinjector device includes a plunger that moves back and forth in theplunger chamber. Movement in one direction allows liquid fertilizer froma liquid fertilizer reservoir to flow into the plunger chamber andmovement of the plunger in the opposite direction injects the liquidfertilizer from the plunger chamber into the water. The mechanicalinjector device is coupled to the paddle wheel which causes movement ofthe plunger in the plunger chamber in at least one direction. Springbias can cause movement of the plunger in the other direction. Themechanical injector device can be disabled to stop fertilizer injectionwhile still allowing rotation of the paddle wheel. The paddle wheel iscoupled to the mechanical injector device through a plunger gear whichrotates, and interacting camming surfaces which project from the plungergear and from a ratchet.

U.S. Pat. No. 6,969,011 to Palmer describes a chemical additivedispensing device for use with a station of a sprinkler-based irrigationsystem that includes a fluid diversion housing and a container forstoring a chemical additive. The fluid diversion housing includes anin-flow channel formed therein that is in fluid communication with aninput port and the container. An out-flow channel is also formed withinthe fluid diversion housing and is in fluid communication with an outputport and the container. In operation, the container fills with fluidfrom the in-flow channel such that the fluid mixes with the chemicaladditive. Once the container is filled with fluid, the mixture of fluidand chemical additive is diverted through the out-flow channel of thefluid diversion housing to the outlet port such that the fluid chemicaladditive mixture is distributed to the rest of the irrigation system andparticularly through sprinklers onto a lawn and/or plants.

U.S. Pat. No. 6,942,128 to Walter describes an automatic dispenser forunderground sprinkler-systems. The unit is placed before the zone valvesof the sprinkler system. The unit is designed to disperse fertilizerinto a tank chamber below a discharge tray. The fertilizer dissolves inthe water and is distributed/dispersed to the appropriate sprinklersystem zone. The discharge tray has multiple chambers based on thenumber of zones in the sprinkler system. The chambers in the dischargetray can hold various capacities based on the area covered by each zonewithin the sprinkler system. The discharge tray turns to dispense thefertilizer as the sprinkler system changes from zone to zone. Thedischarge tray is automatically moved. The chambers are manuallyrefilled based on the frequency of yard fertilization. The unit has anaccess from the top to the discharge tray for filling chambers withfertilizer material.

U.S. Pat. No. 6,722,583 to Restaino et al. describes a lawn sprinkleraccessory with a hollow body defining a chamber for holding lawntreatment material, such as fertilizer, herbicide or insecticide. Theaccessory body has a hollow water inlet arm on one side and a hollowwater outlet arm on the opposite side of the chamber. An access openingwith a removable closure in one end of the accessory body enables theinsertion of lawn treatment material into the chamber and its removalfrom the chamber.

U.S. Pat. No. 6,540,156 to Martin describes a fertilizer and irrigationapparatus that includes an inflow pipe, a shunt pipe connected to theinflow pipe, and a chemical additive assembly connected in parallel tothe shunt pipe. An outflow pipe is also connected to the shunt pipe. Aportion of the inflow pipe, the shunt pipe, the chemical additiveassembly, and the outflow pipe are all above ground. The chemicaladditive assembly includes a quantity of a chemical additive. A manifoldis connected to the outflow pipe. A plurality of in-ground distributionconduits are connected to the manifold, wherein each of the distributionconduits includes at least one above-ground sprinkler head. In addition,an auxiliary inflow assembly can be connected to the inflow pipe so thatchemical additives can be supplied to the fertilizer and irrigationapparatus from an outside source.

U.S. Pat. No. 6,267,303 to Francis describes a sprinkler systemfertilizer injector that comprises a device for injecting liquidchemical solutions into the flow of a lawn sprinkler system. The deviceis said to allow the user to easily attach and remove chemical jarswithout the risk of losing the prime on the pump.

U.S. Pat. No. 6,206,046 to Finley describes a lawn and garden chemicaldispensing system that employs an I.V.-style collapsible bag as a waterflow controlled dispenser of liquid or water-soluble beneficialchemicals for sprinkling systems. The system consists of a stand, achemical vessel, a vessel sleeve, a vessel cap with dual port(internal/external) bulkhead union, an optional filter attachment, achemical feed tube, and a control valve tap connected to a water flowsupply.

U.S. Pat. No. 6,173,732 to Davis et al. describes a chemical feedingsystem for adding either liquid or 100% water soluble solid chemicalsincluding fertilizer, insecticide and a herbicide to a lawn sprinklersystem either above or below ground level. The system has one or twovertically oriented mixing chambers containing a removable spongefilter. An effluent tube is attached to the bottom of the mixing chamberfor recycling through an adjustable flow meter valve. A drain tube witha shutoff valve and a one-way check valve leads to the main sprinklersystem.

U.S. Pat. No. 5,836,518 to Jester describes a fertilizer sprinklersystem including a pipe system adapted for flow of liquid therethrough.The pipe system is comprised of an open inboard portion, a closedoutboard portion and an intermediate portion. The inboard portion iscoupled to a main water line. The intermediate portion is defined by afirst vertical member, a horizontal member and a second vertical member.The intermediate portion further has a lower horizontal member having afirst end in fluid communication with the first vertical member and asecond end in fluid communication with the second vertical member. Thelower horizontal member has an intermediate segment having an integrallid extending downwardly therefrom. The lid has an inlet port and anoutlet port therethrough. A fertilizer container removably couples withthe lid of the pipe system. A plurality of outlet valves are positionedwithin the outboard portion of the pipe system. The plurality of outletvalves are adapted for coupling with sprinklers.

U.S. Pat. No. 5,366,159 to Childers describes an automatic fertilizingapparatus which injects fertilizer directly into the water stream of asprinkler system. Each time the sprinkler system is activated, apredetermined amount of fertilizer is dispensed into the water stream.The apparatus can be controlled to dispense fertilizer only thrusprinkler lines determined by the user.

U.S. Pat. No. 5,364,030 to Murdock et al. describes a solution injectorfor underground sprinkler systems comprising an intake pipe connectedwith a bypass pipe at a system inlet pipe “T”, a tank, and an outflowpipe connected at one end to the tank and at the other to the bypasspipe. The intake pipe is connected to the tank through an intake valveand an intake hose, and the solution injector further comprises a bypassvalve installed on the bypass pipe between the system inlet pipe “T” andthe system outlet pipe “T”.

U.S. Pat. No. 5,303,729 to DeMarco describes An automatic fertilizingdevice for introducing lawn care chemicals such as fertilizer,herbicides, insecticides, and fungicides into a sprinkler system,comprising a container having a control plate insert to divide thecontainer into an upper and lower volume. The container and controlplate are mounted to a flow head, such that the flow head controls theamount of chemicals drawn from the container and dispersed into the mainwater line.

U.S. Pat. No. 5,199,645 to Anderson et al. describes a conversion kitfor converting an existing sprinkler system liquid supply line into ageneral purpose soluble chemical application device is used to applyinsecticides or fertilizer. The easily installed kit mixes dry chemicalswith an existing pressurized liquid to form and expel appropriatetreatment solution. Spent dry chemicals can be easily replaced in aremovable canister. Chemicals from conventional bulk packages orspecially prepared packets may be used. A safety interlock shutoff valveis provided to prevent pressurization of the system while chemicals arebeing replaced. A vacuum breaking air vent valve is provided to allowdrainage of liquid from the system. All components are enclosed withinand supported by a single housing.

U.S. Pat. No. 5,178,181 to Craig describes an applicator for use with asprinkler line system. The applicator comprises a fertilizer containerwith integrally formed internal inlet and outlet tubes. Water is fedthrough an inlet-outlet tube into the bottom of the fertilizercontainer, where it dissolves or dilutes some of the solid or liquidfertilizer and forms a leached, concentrated solution. This concentratecontinuously rises through the fertilizer and into the outlet tube whereit drains downwardly. The concentrate is then diluted with water comingthrough the inlet-outlet tube including a venturi, the size of whichcontrols the flow rate of the concentrate. The diluted concentrate isthen passed into the sprinkler system for application to vegetation. Thebore arrangement of the applicator enables the device to be drained andthen filled with fertilizer, followed by running water through thefertilizer at a selected time. This is said to render the operation moreautomatic.

BRIEF SUMMARY OF THE INVENTION

A dispenser for attachment to a sprinkler system is adapted to receiveor connect to a disposable container filled with a water-solublechemical or an aqueous solution. The container is designed such that theuser is not exposed to the chemical or solution when attaching orremoving the container from the dispenser.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

FIG. 1 depicts a lawn sprinkler system equipped with a chemicaldispenser according to a first embodiment of the invention.

FIG. 2 illustrates a chemical dispenser according to a second embodimentof the invention installed in the supply line of an in-ground sprinklersystem.

FIG. 3 is a cross-sectional view of a portion of the chemical dispenserand chemical container of the system illustrated in FIG. 1.

FIG. 4 is an enlarged cross-sectional view of the portion indicated inFIG. 3.

FIG. 5 is a cross-sectional view taken along line 5-5 in FIG. 4.

FIG. 6 is a partially cut-away, exploded view of the connector portionof the chemical dispenser illustrated in FIGS. 1 and 3.

FIG. 7 is a cross sectional view of the chemical dispenser according tothe embodiment shown in FIG. 2.

FIG. 8 is an alternative embodiment of the portion shown in the dashedcircle in FIG. 7.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, a typical in-ground lawn sprinkler system 10includes water line 12 for supplying fresh water from a pressurizedsource—e.g., a community water system, a well, a spring, surface wateror the like. Backflow preventer or anti-siphon valve 14 may be includedin line 12 to prevent the contamination of the water source in the eventof a loss of supply pressure. The illustrated system is comprised of twozones, each comprising a branch line 22, at least one sprinkler head 28,and an electrically-actuated solenoid valve 24. Electrical conductors 26connect valves 24 to a central control station (not shown) which maycomprise a timer for opening and closing selected valves 24 atpre-selected times. In operation, a selected valve 24 may be opened,causing water to flow from supply line 12, through the branch line 22downstream from the selected valve 24 and out onto lawn 30 by way of thesprinkler head(s) 28 connected to branch line 22. The simplifiedsprinkler system 10 of FIG. 1 comprises only two zones, each having asingle sprinkler head. It will be understood by those skilled in the artthat an actual sprinkler system may have any number of zones and thenumber of sprinkler heads per zone may be limited by the supply pressureand the size of the pipes and fittings comprising the system. Theinvention is not limited to use with lawn sprinkler systems, but may beused in conjunction with any irrigation system. Even residential systemsmay include separate zones for watering shrubs, foundations, planters,and the like. The present invention is applicable to all such systems.

FIG. 1 also illustrates one method for installing the system of thepresent invention in an existing, in-ground sprinkler system. A sectionof supply line 12, downstream of backflow preventer 14 may be removedand elbows 16 and risers 18 installed so that a portion of supply line12 is accessible, preferably above grade. This portion of supply line 12may include union 20 for ease of installation. Chemical dispenser 36 isplumbed in series with supply line 12. Chemical container 34 is shownmounted to dispenser 36. The system may include optional cap or plug 38for ensuring the watertight integrity of dispenser 34 when a chemicalcontainer is not mounted thereon. Plug 38 may have the same threadconfiguration as the neck of container 34 such that it connects todispenser 36 in the same way as a chemical container 34. Alternatively,cap 38 may be provided with separate connection means for sealingengagement with the body of dispenser 36. As shown in FIG. 1, dispenser36 and the above-ground portion of supply line 12 may be concealed fromview with shrubbery 32.

FIG. 2 illustrates an alternative second embodiment of the inventionwherein chemical container 34′ is mounted below disperser 36′. In thisembodiment, dispenser 36′ includes dip tube 40 for withdrawing a liquidchemical or chemical solution from container 34′ Dip tube 40 may be inthreaded engagement with dispenser 36′ for ease of removal. Plug 38′ maybe used to seal dispenser 36′ when container 34′ and dip tube 40 are notpresent.

Also shown in FIG. 2 is optional bypass line 21 and bypass valve 19connected between risers 18. Bypass valve 19 may be a 3-way valve whichmay direct the flow of water from supply line 12 to either dispenser 36or through bypass line 21 to the distribution system. In someembodiments, bypass valve 19 may be an electrically-actuated valve andelectrical control lines 26 may receive control signals from a remotetimer and/or control station (not shown).

FIG. 3 is a cross-sectional view of dispenser 36 according to theembodiment shown in FIG. 1. As shown by the outlined directional arrowsin the drawing, irrigation water from supply line 12 flows through mainpassage 42. Aspirator passage 44 is orthogonal to main passage 12 and ofsmaller diameter such that water flowing through main passage 42 createsa suction in aspirator line 44.

In the embodiment shown in FIG. 3, chemical container 34 is comprised ofa bottle having externally-threaded neck 46. Threaded neck 46 mayaccommodate a screw-type cap to contain liquid chemical 50 in container34 when it is not mounted on dispenser 36. Shoulder 52 may be formed onbottle neck 46 to limit the seating depth of neck 46 ininternally-threaded connector 48 of dispenser 36.

The body of dispenser 36 may be machined from any suitable material suchas a metal or metal alloy or may be molded with a thermoplastic materialsuch as PVC. In FIG. 3, threaded connectors are used to attach dispenser36 to water supply line 12. Other connection means, including thosewell-known in the pipe fitting art, may be used. In embodiments whereinthe body of dispenser 36 is formed of a synthetic polymer, theconnection may be a solvent-welded connection.

It will be appreciated that in order to attach a container of liquidchemical to a dispenser 36 of the type illustrated in FIGS. 1 and 3, itis necessary to invert the container. In order to prevent the chemicalfrom spilling during this operation, it is preferable to equip thecontainer 34 with valve means. One particular preferred embodiment of avalve means is illustrated in FIGS. 3 and 4.

Referring now to FIG. 4, valve insert 56 has U-shaped perimeter section62 which may connect to rim 54 of neck 46 of container 34 in sealingengagement. Container 34 may be a blow-molded, disposable, plasticbottle.

As may also be seen in FIG. 5, valve insert 56 comprises concentricouter wall 57 (which may be a press fit in bottle neck 46), intermediatewall 58 and inner wall 59. Openings 60 in the section betweenintermediate wall 58 and inner wall 59 are provided for the passage ofair. Central channel 64 of valve insert 56 is sealed at its inner end byvalve 66. In the illustrated embodiment, valve 66 is fabricated from anelastomeric polymer material. The perimeter flap 68 of valve 66 sealsapertures 60 and the central portion of valve 66 substantially sealscentral channel 64 of valve insert 56. The center of valve 66 has agenerally cylindrical region of reduced thickness which forms septum 67.Slit 69 is provided in septum 67 to permit the flow of liquid chemical50 from container 34 in response to suction produced by aspirator 44.Preferably, slit 69 is produced by making a cut in septum 67—i.e., slit69 has no appreciable width and the sides of slit 69 seal against eachother and substantially prevent the flow of liquid chemical 50 out ofcontainer 34 when it is inverted with normal, ambient pressure presenton the open side of valve 66.

Referring now to the exploded view provided in FIG. 6, connector insert73 includes cylindrical probe 70 having O-ring 75 in a groove on itsouter circumference for sealing against the interior wall of centralchannel 64 of valve insert 56. Probe 70 has a central passageterminating in orifice 71. The feed rate of chemical 50 may be alteredby varying the size (diameter) of orifice 71. A pair of transverse slots72 are provided in the upper surface of the body of connector insert 73.These slots provide a passageway for air to enter container 34 as liquid50 is withdrawn. The outer, circumferential surface of connector insert73 has threads 74 for engagement with threaded connector 48 of dispenser36. Threads 74 have gap(s) 76 substantially aligned with slots 72 toprovide a passageway for air. Slots 72 also provide an engagementsurface for a tool used to install (or remove) insert 73 in threadedconnector 48.

Connector 48 includes circumferential ring or ridge 80. Connector insert73 includes corresponding ring or ridge 82. O-ring 84 fits between rings80 and 82 for sealing engagement of connector insert 73 in threadedconnector 48. Screen 86 may be provided in the central passageway ofdispenser 36 for preventing the entry of undissolved chemicals orforeign matter into the irrigation system to which it is attached.

The second illustrated embodiment of the invention is depicted in FIGS.2 and 7. In this embodiment, container 34′ attaches to dispenser 36′ onits undersurface—i.e., container 34′ need not be inverted in order toattach it to dispenser 36′.

Container 34′ may be sealed by a screw-on cap (not shown) and membrane90. Membrane 90 may be formed of any suitable material as is well knownin the art. Examples of sealing membrane materials include plasticpolymers, metal foils, treated papers and laminates comprising one ormore of these materials. Dip tube 40 is designed to pierce membrane 90.To that end, dip tube 40 may comprise sharpened tip 100. Dip tube 40 mayalso comprise section 98 of enlarged diameter. Enlarged diameter section98 is provided near the distal end of tube 40 such that, when tip 100pierces membrane 90 and section 98 is forced through membrane 90 alarger opening 92 than that merely required to accommodate the smallerdiameter section of dip tube 40 is created. An annular opening 92surrounding tube 40 permits air to enter headspace 93 via vent port 94and vent passageway 96 as liquid chemical 50 is withdrawn from container34′ thereby relieving the partial vacuum that would otherwise be createdand which would substantially stop the aspiration of fluid through tube40. Dip tube 40 may comprise threaded connector 104 and seal 102 topermit the user to remove and replace dip tube 40. As discussed above,it may be advantageous to remove dip tube 40 in order to permit theinstallation of cap or plug 38′ when container 34′ is not in place ondispenser 36′.

FIG. 8 depicts an optional check valve 106 that may be provided in ventpassageway 96 for preventing the evaporation of liquid chemical 50 fromcontainer 34′ and/or preventing the possible discharge of liquidchemical 50 through vent passageway 96 and vent port 94 in the eventthat the discharge side of dispenser 36′ becomes blocked.

Valve 106 may be fabricated from natural rubber or a syntheticelastomeric polymer material. The valve action may be effected by meansof flap 108 connected to the body of valve 106 via living hinge 112.Circumferential ridge 110 may be provided to secure valve 106 in acorresponding groove in the wall of passageway 96.

Liquid chemical 50 may be any water-soluble or water-miscible chemical.Examples include fertilizers, pesticides, herbicides, fungicides,growth-enhancing agents, abscission agents, wetting agents, and thelike. Oil-based chemicals may also be dispersed as an emulsion in waterusing the dispenser of the present invention.

The operation of the embodiment of the invention illustrated in FIGS. 1and 3-6 will now be described with reference to those drawing figures.The user selects a bottle 34 containing the desired treatmentchemical(s) and removes the cap from the bottle. If installed, the useralso removes plug or cap 38 from dispenser 36. Bottle 34 is inverted andscrewed into threaded connector 48 until shoulder 52 is seated on therim of connector 48 or valve insert 56 contacts the flat, upper surfaceof connector insert 73. During this installation operation, valve 66substantially prevents the loss of chemical 50 from bottle neck 46.

Water flowing through main passage 42 produces a suction in aspiratorpassage 44. This suction is sufficient to draw liquid chemical 50through slit 69 in septum 67 and into aspirator passage 44. Liquidchemical 50 mixes with water in main passage 42 of dispenser 36 andcontinues to mix with the water as it flows through the distributionsystem to the selected zone and out through sprinkler head 28. As liquidis withdrawn from container 34, a partial vacuum is produced. This isrelieved by ambient air entering gap 81 in connector 48 and followingthe path depicted by the arrows in FIG. 4. Flap portion 68 of valve 66opens in response to the reduced pressure within container 34 and airenters the interior of the container through apertures 60 in valveinsert 56. Chemical feed continues until the contents of container 34are exhausted or the flow of water through main passage 42 ceases.Container 34 may remain in place on dispenser 34 even when empty withoutadversely affecting the operation of sprinkler system 10. Alternatively,it may be removed and replaced with plug 38.

The operation of the embodiment illustrated in FIGS. 2, 7 and 8 issimilar. Cap 38′ is removed from dispenser 36′ (if installed). Acontainer 34′ of liquid chemical 50 is selected and its top (not shown)is removed. If it was previously removed, dip tube 40 is installed byscrewing threaded connector 104 into the body of dispenser 36′. Membrane90 of container 34′ is now pressed against tip 100 of tube 40 withsufficient pressure to puncture membrane 90 and force larger diametersection 98 through membrane 90 forming a hole therein that is largerthan the smaller diameter section of tube 40. Container 34′ is screwedonly dispenser 36′ and the flow of irrigation water through it is begun.The flow of water across the upper end of dip tube 40 produces a suctionin the tube which withdraws liquid chemical 50 from container 34′ whereit mixes in the main passageway of dispenser 36′ and continuesdownstream and out through sprinkler heads 28 in the selected zone. Thepartial vacuum produced in headspace 93 by the withdrawal of liquidcontents of container 34′ is relieved by ambient air entering headspace93 via vent port 94 and vent passageway 96 as shown by the arrows inFIGS. 7 and 8. Optional check valve 106 prevents supply water from mainfeed line 12 from passing through tube 40, into the interior ofcontainer 34′ and out through vent port 94 when all downstream valvesare closed. Container 34′ also may remain in place on dispenser 34′ evenwhen empty without adversely affecting the operation of sprinkler system10. Alternatively, it may be removed and replaced with plug 38′.

It should be appreciated that container 34 (or 34′) may be a disposablecontainer. This feature, together with the action of valve 66 (in thefirst embodiment) or membrane 90 (in the second illustrated embodiment)provides significant safety benefits to the user. The chances ofinadvertent contact with liquid chemical 50 (which may be toxic) aregreatly reduced when the user need handle only the exterior of container34 and disposes of the container following use. Valve 66 (or membrane90) prevents liquid chemical 50 from splashing or spilling fromcontainer 34 (or 34′) during handling when its cap or lid is removed.

As shown in FIG. 2, dispenser 36 or 36′ may be bypassed in certainembodiments with bypass valve 19 and bypass line 21. In this way,chemical 50 may be applied only to certain selected zones and/or appliedonly during a portion of the watering cycle. For example, it may bedesired to apply a weed-and-feed chemical only to those zones ofsprinkler system 10 that apply water to lawn surfaces and not to zonesfor shrubs or gardens. If bypass valve 19 is electrically actuated, itmay be connected to a central control station (not shown) that selectsits position in response to the particular zone being watered and/orselects a certain valve position for a certain time interval.

Although the invention has been described in detail with reference tocertain preferred embodiments, variations and modifications exist withinthe scope and spirit of the invention as described and defined in thefollowing claims.

What is claimed is:
 1. A liquid chemical dispenser for an irrigationsystem comprising: a body having a passage for the flow of irrigationwater; a water inlet port on a first side of the body in fluidcommunication with the water passage, the inlet port having a firstdiameter; a water discharge port on a second side of the body in fluidcommunication with the water passage, the discharge port having adiameter substantially equal to the first diameter; an aspirator passagesubstantially orthogonal to and in fluid communication with the passagefor the flow of water; a removable chemical container for containing aliquid chemical for mixing with irrigation water flowing through thebody connected to the body and in fluid communication with the aspiratorpassage, the container having an opening at a first end thereof; amembrane which, when intact, seals the opening in the chemicalcontainer; a dip tube in fluid communication with the aspirator passagefor withdrawing liquid chemical from the chemical container, the diptube consisting of a substantially cylindrical tube having a threadedconnector and seal at a first end thereof, a sharpened tip configuredfor piercing the membrane at an opposing second end thereof, and asection of increased diameter proximate the sharpened tip thereof sizedand configured such that when the tip pierces a membrane on the chemicalcontainer and the dip tube is inserted in the opening so made, asubstantially annular opening in the membrane is produced around the diptube.
 2. A liquid chemical dispenser as recited in claim 1 furthercomprising a vent port in the body for admitting ambient air in responseto reduced pressure within the chemical container, the vent port beingin fluid communication with the substantially annular opening in themembrane.
 3. A liquid chemical dispenser as recited in claim 2 furthercomprising a check valve in fluid communication with the vent portconfigured to prevent the flow of liquid in the container out of thevent port.
 4. A liquid chemical dispenser as recited in claim 3 whereinthe check valve is a flap valve comprised of an elastomeric polymer.